Force and Laws of Motion quiz

The SI unit of force is:

The measure of inertia of a body is its:

Momentum is the product of:

Which law gives the relation F = ma?

When a gun is fired, it recoils because of:

A force of 10 N acts on a mass of 2 kg. The acceleration produced is:

The SI unit of momentum is:

Which has more inertia?

Action and reaction forces act on:

When the net force on a body is zero, the body:

Why do we shake a branch of a tree to make fruits fall? (2 marks)

Why does dust come out of a carpet when it is beaten with a stick? (2 marks)

Why are seat belts provided in cars? (2 marks)

How does a karate player break a slab of ice with a single blow? (2 marks)

Why is it advised to tie luggage kept on the roof of a bus with a rope? (2 marks)

A horse pulls a cart. If action equals reaction, how does the cart move? (2 marks)

What happens to the momentum of a body if its velocity is doubled? (2 marks)

Why does a high jumper land on a cushioned or sand bed? (2 marks)

Explain how a rocket moves upward using the third law. (2 marks)

Give two examples of inertia of motion from daily life. (2 marks)

Find the momentum of a 50 kg boy running at 4 m/s, and of a 0.15 kg cricket ball moving at 40 m/s. (3 marks)

A force acts for 10 s on a stationary body of mass 100 kg, after which the force ceases to act. The body moves through 50 m in the next 5 s. Find the velocity acquired and the magnitude of the force. (3 marks)

An object of mass 1 kg travelling in a straight line at 10 m/s collides with and sticks to a stationary wooden block of mass 5 kg. Find the total momentum before the impact and the velocity of the combined object. (3 marks)

The velocity of a 5 kg object changes from 3 m/s to 7 m/s in 2 s under a constant force. Find the initial and final momentum and the force. (3 marks)

A girl of mass 40 kg jumps with a horizontal velocity of 5 m/s onto a stationary cart of mass 3 kg with frictionless wheels. Find her velocity as the cart starts moving. (3 marks)

Read the passage and answer the questions. In a cricket match, a fielder catching a fast ball moves his hands backwards as he catches it. A beginner who keeps his hands stiff hurts his palms. (i) Why does moving the hands back reduce the force? (ii) Which law of motion explains this? (iii) If a 0.15 kg ball at 30 m/s is stopped in 0.1 s, find the average force. (5 marks)

Read the passage and answer the questions. A bus is moving at high speed when the driver suddenly applies the brakes. The passengers lurch forward, and a bag on the seat slides forward. (i) Name the property of matter that explains this. (ii) Why do the passengers lurch forward? (iii) What happens when a stationary bus suddenly starts? (5 marks)

Read the passage and answer the questions. A rifle of mass 4 kg fires a bullet of mass 10 g with a velocity of 400 m/s. The shooter feels a push on his shoulder. (i) Find the momentum of the bullet. (ii) Find the recoil velocity of the rifle. (iii) Which law explains the recoil? (5 marks)

Read the passage and answer the questions. A student pushes a heavy almirah but it does not move. When two friends help, it starts moving slowly and then moves easily. (i) Why did the almirah not move at first? (ii) What kind of forces act when it is at rest? (iii) Why does it move more easily once it starts moving? (5 marks)

Read the passage and answer the questions. A boat in a lake is at rest. A man on the boat jumps forward onto the shore and the boat moves backward. (i) Which law explains the boat moving back? (ii) Name the quantity that is conserved. (iii) If the man has mass 60 kg and jumps at 2 m/s, and the boat is 120 kg, find the boat's velocity. (5 marks)

State Newton's second law. Derive F = ma from it and define one newton. Draw a diagram showing a force acting on a trolley and its acceleration. (6 marks)

State the law of conservation of momentum and derive it for the collision of two balls using the third law. Draw diagrams for before, during and after the collision. (6 marks)

Explain the three types of inertia: of rest, of motion and of direction, with a labelled diagram of an example for each. (6 marks)

Draw a diagram of two spring balances connected together and pulled. Explain how this demonstrates the third law of motion. (6 marks)

Draw velocity-time graphs for an object (i) at rest (ii) moving with uniform velocity (iii) accelerating under a constant unbalanced force. Explain each using Newton's laws. (6 marks)